The 50mm PAK38 was a potent anti-tank gun

The 50mm PAK38's that decimated C Squadron of the 3rd Royal Tanks on the tenth day of the Crusader battle were potent anti-tank guns, especially in late 1941. My copy of Anti-Tank Weapons, from the WW2 Fact Files, says that the 50mm PAK38, firing conventional AP shot could penetrate 61mm at 500 meters. C Squadron was "taken out" at almost point-blank range. In fact, my copy of Weapons of the Third Reich shows that at 30mm angles, the PAK38 could penetrate 73mm at point blank range and 67mm at 250 meters. This page has the armour thicknesses on the Stuart. The thickest armour on the Stuart was 51mm, so the 50mm PAK38 could easily penetrate the Stuart's armour at close range.